1. Field of the Invention
The present invention relates to a railroad test vehicle extending in a longitudinal direction along a railroad track having two rails and adapted to run on the track, which comprises a measurement axle comprising two flanged wheels rotatable about a measuring axis extending transversely to the longitudinal direction and adapted to run on the rails, and means connecting the measurement axle to an underside of the vehicle.
2. Description of the Prior Art
Such railroad test vehicles are designed among other things to measure the strength of the attachment of the track rails to the crossties, which is important in maintaining the integrity of the railroad track. A measurement carriage or axle is used to push against the side of the rail and measure movement of the track rail with respect to the crosstie. The measurement axle assembly must follow the track rails and load the rails vertically and laterally against the inner face of the head of the rails for purposes of testing the attachment of the rails to the crossties. Measurement axles of this kind have been incorporated, for example, as one of the running axles of a railroad test vehicle or have been suspended from an underside of a railroad test vehicle by some type of guidance system.
It is the primary object of this invention to provide a railroad test vehicle wherein the measurement axle is suspended from an underside of the railroad test vehicle for operation separately from the running axles of the vehicle while it may be lifted and lowered for use, when necessary, and stored at will, when not needed. If the measurement axle derails, the overall vehicle safety is not endangered. The measurement axle is suspended in such a way that, regardless of the roll, pitch or vertical movement of the railroad test vehicle body on its resilient suspension, or the curvature, profile, alignment and cross-level of the track, the flanged wheels of the measurement axle are always kept on their respective rails and the vertical load always remains perpendicular to the upper surface of the rail.
The above and other objects are accomplished according to the invention in a railroad test vehicle of the first-described type by providing a cross member extending transversely to the longitudinal direction, vertically spaced from an underside of the vehicle and affixed thereto, and means connecting the measurement axle to the cross member and permitting the measurement axle to be freely tilted about an axis extending in the longitudinal direction and to be freely pivoted about an axis extending perpendicularly to the longitudinal direction. The connecting means comprises two trunnions transversely spaced from each other and mounted on the cross member. Each trunnion defines a clearance with the cross member sufficient to enable the trunnion to be freely tilted to either side of the vehicle about the axis extending in the longitudinal direction. A support frame is mounted on each trunnion for pivoting freely about the axis extending perpendicularly to the longitudinal direction. Two pairs of linkages are transversely spaced from each other by the same distance as the transversely spaced trunnions, and each pair comprises an upper swing arm and a lower swing arm spaced from the upper swing arm in a vertical direction. A joint connects each swing arm to the measurement axle, and a hinge connects each swing arm to a respective one of the support frames. At least one pressure cylinder having a vertically extending cylinder axis and exerting a contact force presses the measurement axle against the rails.
With such connecting means, the measurement axle is kept in contact with the railroad track regardless of the movement of the railroad test vehicle on its conventional resilient suspension and regardless of the track curvature. The structure further insures that the pressure cylinders are always aligned in such a manner that the vertical force pressing the flanged wheels of the measurement axle against the rails is always perpendicular to a plane defined by the running surfaces of the rails.
Furthermore, the measurement axle may be pressed against the running surfaces of the rails with a load which is always perpendicular to a line formed by the wheel contact surfaces of the rails engaged by the flanged wheels as the railroad test vehicle moves on its resilient suspension along the track, and the track curvatures and/or the track cross level changes. The measurement axle is so oriented that the flanged wheels thereof are tangent to the rails as the track curvature varies.